package part1;

public class Stereo {
    private static final Stereo INSTANCE = new Stereo();

    public static Stereo getInstance() {
        return INSTANCE;
    }

    public void on() {
        System.out.println("开启立体声");
    }

    public void off() {
        System.out.println("关闭立体声");
    }

    public void up() {
        System.out.println("调大声音");
    }

    public void down() {
        System.out.println("调低声音");
    }
}
